How to Find and Fix Medical Bill Errors

Upcoding occurs when a provider bills for a more expensive service than what was actually performed. The most common example is office visit level inflation — billing a comprehensive visit (CPT 99215) when only a routine follow-up (CPT 99213) was performed. The difference can be $150 or more per visit. Upcoding also happens with procedure codes, where a simple procedure is billed as complex.

The same service is billed twice. This happens frequently when a claim is resubmitted due to a processing error, when a hospital uses both facility and professional billing departments that each enter the same service, or when a multi-day stay generates overlapping charge entries. Operating room supplies, lab tests, and medication doses are especially prone to duplication.

Unbundling is when a provider bills each component of a procedure as a separate service rather than using the single, comprehensive code that should apply. For example, a standard blood panel might be billed as 15 separate tests instead of a single panel code — significantly inflating the total cost. The National Correct Coding Initiative (NCCI) maintains code pairing rules specifically to prevent this.

Balance billing happens when an out-of-network provider bills you for the difference between their charge and what your insurance paid. Under the No Surprises Act (effective January 1, 2022), balance billing is now illegal for emergency services, air ambulances from out-of-network providers, and certain non-emergency services provided by out-of-network clinicians at in-network facilities (such as anesthesiologists, radiologists, and pathologists).

Data entry errors — wrong dates of service, incorrect patient information, wrong diagnosis codes, services attributed to the wrong patient, or charges for procedures that were cancelled or never performed. These are simple errors but can be costly and are more common than you might expect, particularly in high-volume hospital billing departments.

Your insurance information was entered incorrectly, a secondary insurance was not billed, an in-network discount was not applied, or the bill reflects pre-insurance charges rather than your actual patient responsibility. This is one of the most common errors and often the easiest to fix, because it typically requires the provider to simply reprocess the claim with correct insurance information.

Before disputing anything, you need both documents. Call the provider's billing department and ask for a fully itemized bill showing every CPT code, ICD-10 code, date of service, and charge amount. Separately, get your EOB from your insurer (usually available in your online portal). If the provider pushes back, remind them that you have a legal right to an itemized statement.

Check that every charge on the bill corresponds to a line on the EOB. Verify that insurance adjustments were applied. Confirm the patient responsibility amount matches between documents. Note any charges that appear on the bill but not the EOB — this could mean the claim was not submitted to insurance or was denied.

Go through each line item and ask: "Did I actually receive this service?" Check for charges on dates you were not seen, services you do not recall, and supplies or medications you did not receive. Compare procedure codes against descriptions — if a code description does not match what happened, the charge may be an upcoding error.

Look up the charges on the CMS physician fee schedule, the Healthcare Bluebook (fairhealthconsumer.org), or your state's hospital price transparency tool. Under the Hospital Price Transparency Rule (effective 2021), hospitals must publish machine-readable files of their standard charges. If your bill exceeds Medicare rates by 300% or more, you have strong grounds for negotiation.

Send a written dispute to the provider's billing department. Be specific: list each charge you are contesting, explain why it is incorrect (duplicate, upcoded, not received, etc.), reference your EOB, and state the amount you believe is correct. Request a written response within 30 days. Send via certified mail or the provider's patient portal with a timestamp.

If the bill has errors that are corrected but the remaining amount is still high, you can negotiate. Ask for a cash-pay discount (typically 20-40% off), a payment plan with no interest, financial hardship assistance, or a reduction to Medicare rates. Most providers have financial assistance policies, especially nonprofit hospitals (which are required to under IRS regulations for 501(c)(3) status).

If the billing department is unresponsive or refuses to correct legitimate errors, you have escalation options: file a complaint with your state attorney general's consumer protection division, contact your state's department of insurance if the issue involves insurance processing, report No Surprises Act violations to CMS, or consult a medical billing advocate or attorney.